Support for filaments.



W. R. WHITNEY. SUPPORT FOR FILAMENTS.

APPLICATION FILED JUNE 14, 1907.

1,105;050. Patented July 28, 1914,

Witnesses Inventor %-.A Z.% j I Willis R; h i mey, by a DIttg.

UNlTED STATES PATENT OFFICE.

WILLIS R. WHITNEY, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERALELECTRIC COMPANY, A CORPORATION OF NEW YORK.

SUPPORT FOR FIIPAMENTS.

Specification of Letters Patent.

Patent-ed July 28, 1914.

Application filed June 14, 1907. Serial No. 378,932.

To (ZZZ whom it may concern:

Be it known that I, WVILLIs R. WHITNEY, a citizen of the United States,residing at Schenectady, county of Schenectady, State of New York, haveinvented certain new and useful Improvements in Supports for Filaments,of which the following is a specification.

Metal lamp filaments of tungsten, molybdenum, and other high meltingmetal are, during normal 'use, subject to expansion and contraction byheating, and furthermore, are sometimes subject to progressivecontraction during a considerable portion of their normal life. Theselamp filaments are relatively soft and plastic when running at highincandescence, and therefore, should be supported to prevent saggingwhen the lamp is burned in a horizontal position. Owing to the change inlength of the filament, as above mentioned, this supporting means shouldpreferably-be resilient in character.

My present invention comprises means for supporting such filaments in animproved manner, whereby the danger of contaminating the filament or thevacuum is obviated, and whereby the filament may be protected againstbreakage during transportation.

According to my invention, the supporting means consists of or comprisesa member of refractory metal, such as tungsten or molybdenum, which maybe resilient.

Two embodiments of my invention are illustrated in the accompanyingdrawing, in

' which Figure 1 is a single filament lamp having -a helical tungstensupport for the filament loop; Fig. 2 is a multiple filament lamp inwhich a single tungsten spring serves for all the filaments; and Fig. 3is a perspective view of a simple apparatus suitable for shapingtungsten wire into the helices illustrated in Figs. 1 and 2.

Tungsten as ordinarily obtained is in the form of a dark powder, veryrefractory in character, and possessed of so little coherence that itcan be shaped into wires only by and pliant, and of shaping them intoforms suitable for use according to my invention. The treatments andmanipulations of tungsten hereinbefore referred to and hereinafterdescribed are to. be considered as also applicable to molybdenum, andthe latter is to be regarded as the equivalent of tungsten for thepurposes here set forth.

The wire produced as described in the patents and applications aforesaidis found to be strong and firm and somewhat elastic, but without thecapability of taking a. permanent set and practically devoid ofductility, at least in the sense in which that term is applied to suchmetals as copper, silver, platinum, etc. To shape such a coherent bodyof non-ductile tungsten into a helix, I may make use of the simpleapparatus illustrated in Fig. 3, comprising a platinum mandrel '1supported in a wooden block 2 and heated by a flame 3 burning at the endof a glass tube 4 connected with a source'of gas supply. This mandrel ispreferably maintained at a temperature somewhat below visible rednessor, at least, not sufficiently high to materially oxidize the tungstenwire under treatment. To shape the tungsten wire into a helix, it isonly necessary to insert the wire in a slot 5 cut across the end of themandrel, and to then slowly rotate the mandrel and wind the wirethereon. I will not attempt to explain why this heating of the tungstenchanges it over from the brittle and non ductile condition to the pliantstate, but such is the case.

After the spiral is completed, it may he slipped off the mandrel andused in the lampstructure in any desired Way. One manner of mounting isshown in Fig 1, in which the tungsten spiral 6 is sealed directly in theend of the glass pedestal 7 carried by the lamp stem 8. The spiralserves as a support for the lamp filament 9. This figure is to beregarded as largely diagrammatic and as showing an embodiment which canbe readily modified in a variety of ways. Fig. 2 shows a somewhatdifferent arrangement in which a single tungsten spiral 10 serves for aplurality of filament loops. In this case the glass pedestal '11 of thelamp carries a glass sleeve 12 which is free to move up and down thepedestal except for the action of the tungsten spring 10 by which it isforced outward toward the end of the pedestal. This glass sleeve 12carries a plurality of tungsten wires 13 having hooks 14 in their endsand serving as supporting arms for the lamp filaments. These wires maybe of tungsten and may be bent into shape by use of the apparatus shownin Fig. 3. 3

When tungsten lamp filaments'are running at exceedingly hightemperatures, other elements of the lamp are heated thereby, and unlessthe elements are of vproper material, they are liable to give up gasesand impair the vacuum of the lamp or contaminate the material of thefilament. A

tungsten spring may be inclosed in a lamp Without danger of undergoingchange by heat from the filament, and so can be used in any positionwith safety. Further than this, a tungsten spring retains its elasticproperties at very high temperatures, and therefore remains operative asa spring under conditions where less refractory metals would entirelyfail.

Direct contact between the tungsten filament and the clean andunoxidized tung sten support oflfers no disadvantage, and m fact, offersmany advantages over those constructions in'which the filament is liableto contamination by the material of the support or by gases liberatedtherefrom.

What I claim as new, and desire to secure by Letters Patent of theUnited States, 15,-

1. The combination with a refractory metal filament of supporting meansthere fore by which it is yieldingly supported comprising a coiledspring of tungsten en gaging with the filament.

2. The combination of a tungsten lamp filament and a resilient supporttherefor consisting of tungsten.

3. The combination with a tungsten filament of supporting means thereforcomprising a bent wire of tungsten engaging With the filament.

In witness whereof, I have hereunto set my hand this 12th day of June,1907.

WILLIS R. WHITNEY.

Witnesses: V

BENJAMIN B. Hm HELEN ORFOBD.

